Anion-/cation-directed reaction routes to polymorphic forms of a pyrazole-type ligand and its coordination compounds with zinc. Key structural differences between polymorphs’

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• 作者：Berta Barta Holló ; Katalin Mészáros Szécsényi ; Mária Deli…
• 刊名：Structural Chemistry
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：27
• 期：4
• 页码：1121-1133
• 全文大小：1,440 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Computer Applications in Chemistry
  Physical Chemistry
  Theoretical and Computational Chemistry
  
• 出版者：Springer Netherlands
• ISSN：1572-9001
• 卷排序：27

文摘

Synthetic paths toward the two polymorphs of a monohydrate, one anhydrous polymorph of 1-carboxamidino-5-hydroxy-3-methylpyrazole (hcmp) and two polymorphs of zinc complexes containing hcmp ligand are presented. By choosing ions which are not part of the final product, it is possible to direct the synthesis toward the particular polymorph. In all three modifications of hcmp, the same hydrogen bonding motif appears, leading to formation of similar molecular chains. Differences arise due to different modes of chain aggregation and the presence of solvent water. Analysis of the crystal packing and the energetic features of hcmp polymorphs is made using the PIXEL model. The thermal decomposition processes are examined using differential scanning calorimetry and thermogravimetry. Analysis of crystal packing in the two polymorphs of zinc complex suggests the key role of the hydrogen bonding capacity of the aqua ligand for the appearance of the two polymorphic forms. In both polymorphs of zinc complex, stacking interactions have an important role. However, the enhanced hydrogen bonding capacity of the aqua ligand influences the formation of multistacking arrangement.KeywordsPolymorphismPIXEL calculationsIntermolecular interactionsPyrazole-based ligand and Zn complex